A positive displacement expander of the type which generates power by the expansion of high pressure fluid is known in the conventional technology (see, for example, JP-A-2004-190938). This type of positive displacement expander is employed, for example, in a refrigeration apparatus configured to perform a vapor compression refrigeration cycle.
Such a refrigeration apparatus includes a refrigerant circuit in which a compressor, a cooler, a positive displacement expander, and an evaporator are connected by piping, and the refrigerant circuit performs a vapor compression refrigeration cycle. In the positive displacement expander, sucked-in high pressure refrigerant is discharged after expansion and the resulting internal energy is converted into power for rotating the compressor.
Incidentally, the suction flow rate of the positive displacement expander during the suction process and the discharge flow rate of the positive displacement expander during the discharge process are not constant, and refrigerant pressure pulsation (pressure variation) occurs at the inlet and outlet sides and pressure loss is caused due to the pressure pulsation. To cope with this, the refrigeration apparatus is equipped with an accumulator at either the inlet or the outlet side of the positive displacement expander for the purpose of pressure pulsation inhibition. In addition, such a pressure pulsation triggers pressure loss and vibration in the equipment.